124 J. T. CUNNINGHAM. 



year. The ovary was preserved with a mixture of chromic 

 acid yL per cent., and osmic acid J^- per cent. The eggs in 

 the sections from this ovary measure from. 'Ol to '06 ram. in 

 diameter. In none of these eggs have I been able to distin- 

 guish the yolk nucleus with certainty. All of the eggs men- 

 tioned have passed the stage of subdivision, they are no longer 

 multiplying germ cells, but definite eggs in the stage of 

 maturation. The germ cells and germinal epithelium in 

 these sections are too much shrunken by the preserving 

 reagents, and too little differentiated by the staining to be 

 studied. 



The nucleus of the smallest eggs exhibits a single rather 

 large nucleolus 2-5 ju in diameter in the central part, though 

 not exactly at the centre, and some smaller, not very distinct 

 nucleoli which appear to be thickenings of the nuclear mem- 

 brane. In the larger eggs there are several nucleoli of very 

 different sizes ; usually one is very large, reaching 7*5 fx, or 

 even "01 mm. in diameter, while the rest are much smaller. All 

 the nucleoli are situated close to the nuclear membrane, and 

 they are usually spherical in shape, but occasionally they are 

 hemispherical, the fiat side being in contact with the nuclear 

 membrane. It is possible that the large nucleolus divides, 

 but I have only once seen a condition which could be con- 

 sidered a stage of division, namely, two nucleoli of equal size 

 almost in contact. Occasionally in these, as in other sections, 

 a nucleolus is seen outside the nuclear membrane, but when- 

 ever I have seen this I have seen evidence that the external 

 nucleoli had been removed from their proper position me- 

 chanically in the process of preparation. The central space 

 of the nucleus is occupied with a network of fine threads, 

 according to the prevalent view representing the chromatin, 

 the nucleoli being composed of a material somewhat different 

 in properties. 



The sections I have next to describe were prepared from the 

 ovary of a plaice 7^ inches long, killed in March. The tissue 

 was fixed in a mixture of chromic and osmic acid, each to the 

 strength of yV P^^" cent., the tissue remaining in this mixture 



